Answer:
d) Before cooling begins, the temperature of the water is 22°C
Explanation:
Option A
If t=7 minutes
D=-7/5t+22
=-7/5(7)+22
=-49/5+22
=-49+110/5
=61/5
=12.2°C
Change in temperature=12.2°C-22°C
=-9.8°C
Option B
If t=5 minutes
D=-7/5t+22
=-7/5*5+22
=-7+22
=15°
Change in temperature=15°-22°
=-7°
Option C
The temperature of the ice must be less than 22°C
Option D
D=-7/5t+22
When ice is not placed, t=0
D=-7/5t+22
=-7/5(0)+22
=0+22
=22
Temperature of the water before cooling=22°